Something I have used with some rather interesting success on winter cut VM is a big long screwdriver. I start with a dull heavy scraper to get most of the bark off before getting close to the wood. Once the bulk of the bark is off, I'll holding both ends of the screwdriver, one on the handle the other out near the tip. I press downward while I rub back and forth over the bark/cambium. After a bit of time the cambium thats seemingly stuck hard to the wood starts to lift. I've not had any problems with this violating the back either. Once you get the hang of it, you'll find how best to do it without harming the wood. I usually start on the belly side of the stave just for practice.
Give it a shot, let me know if its just me or it its a fluke.
certainly works for VM tho.
Mike